Automobiles and other vehicles have come to employ safety systems which include radar technologies for detecting a location of an object or target with respect to the vehicle so that a driver or a collision-avoidance device can react accordingly. A radar system includes a transmitter for sending out a source signal and a receiver for receiving an echo or reflection of the source signal from the target. The reflected signal is sampled at a selected sampling frequency and the sampled data points are entered into a Fast Fourier Transform (FFT) in order to determine a Doppler frequency for the returning signal. A relative velocity of the target with respect to the vehicle is determined from the Doppler frequency.
The radar system transmits a series of chirp pulses, resulting in a series of echo signals. The chirp pulses are transmitted in groups known as transmission frames, with each frame including a plurality of chirp signals. In order to operate the radar system within an operational temperature range, transmission frames are separated by a down-time period having a selected duration to allowing cooling. Due to the down-time separating transmission frames, the size of the FFT that can be performed is limited to the number of echo signals obtained from a single transmission frame. It is known, however, that the more signals that are sampled, the greater the resolution of the Doppler frequency. Accordingly, it is desirable to provide a method for increasing the number of the samples that can be provided to the FFT in order to improve Doppler resolution.